The document describes the cupola furnace process. The cupola furnace is used to melt iron and produce nodular cast iron. It consists of a cylindrical shell lined with refractory materials. Alternating layers of coke, limestone flux, and scrap iron are charged into the top of the furnace. Air is blown in through tuyeres, producing combustion and melting the charge. Molten iron collects in the well at the bottom and is tapped out once sufficient melting has occurred. Slag also forms and is removed before tapping the metal. The furnace involves different zones including the combustion, reducing, and melting zones.

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3. • Metal ore ----- PIG IRON--- to produce Wrought iron
• 30meter high and 8m diametre.
• Fire proof bricks
• Hot air passed from the bottom
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Wrought iron:
A tough malleable form of iron suitable for
forging or rolling rather than casting,
obtained by liquid pig iron while molten. It is
nearly pure but contains some slag in the
form of filaments.

4. • Due to Density difference the molten metal flows down.
• Coke, limestone and iron ore are poured at the top.
• Air is blown in through tuyers.
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Before Reduction After Reduction

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8. • 4. blast furnace science
• MTunit 1
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9. • Used to produce gray, nodular cast iron
• Also used for melting copper base alloy
• Fuel for cupola is good grade low sulphur coke,
anthracite coke(hard and rich carbon).
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Nodular cast iron

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11. • Cylindrical shell welded or riveted 10mm thick plates.
• Open at both top and bottom lined with firebricks and
clay.
• Castlron leg supports it.
• At bottom a swing door helps to left the content after
the melting.
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12. • Air from the blower comes form the blast pipe and enters
wind box. And supply evenly to all tuyeres.
• Tuyeres extend by a steel shell and refractory wall to the
combustion zone and supply air.
• A 75cm dia cupola have 3-4 tuyeres.
• Volume meter helps to measure the volume of air
passing to the combustion zone.
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13. • Air pressure is 12-16 sq in.
• A cupola uses 10:1 ratio of iron to coke.
• About 800-900 cubic meters of air is used to melt one ton
of iron.
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14. 1. Preparation of cupola.
2. Lightning the fire in the coke bed.
3. Charging of cupola
4. Melting
5. Slagging and metal tapping
6. Dropping down the cupola bottom
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15. 1) Preparation of cupola:
• Bottom door is dropped – dumped unburned coke , slag
are removed – side wall cleaning – replace damaged
firebricks.
• Cupola block composition
Silica 52-62% Alumina 31 – 43%
Titania 1.5-2% Fluxing oxides 3-6%
Bottom door closed- 10cm sand is rammed have some
sloping towards tap hole.
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16. 2) Lighting the fire:
•
• Ignited in Dry wooden pieces(OR electric, gas tourches),
air is supplied to burn coke.
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17. 3)Chargingof cupola:
• After the ignition form charging door addition of alternate
layers of COKE, Flux (limestone), and IRON is
supplied upto the level of charging door.
• Flux used to remove the impurities
• Coke- good low sulphur coke, anthracite coke
• Iron: pig iron, scraps, returns (gates, sprue, risers,
defective castings)
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18. 4) Melting:
• Initially one hour takes for preheating the
charge.(soaking period)
• Now the air blast is turned on.
• After ten minutes molten iron starts accumulating near
the tap hole.
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Combustion system
C + O2 ——→ CO2 + Heat
Si + O2 ——→ SiO2 + Heat
2Mn + O2 ——→ 2MnO +
Heat
Reducing zone
CO2 + C (coke) ——→ 2CO + Hea
Melting zone
3Fe + 2CO ——→ Fe3C + CO2

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Combustion system
C + O2 ——→ CO2 + Heat
Si + O2 ——→ SiO2 + Heat
2Mn + O2 ——→ 2MnO +
Heat
Reducing zone
CO2 + C (coke) ——→ 2CO + Heat
Melting zone
3Fe + 2CO ——→ Fe3C + CO2

20. 5) Droppingdown the bottom:
• At the end the charging is stopped.
• All the contents in the cupola is allowed to melt.
• Air blast is shut off.
• The prop in the bottom door is knocked down.
• And quenched in water and use in the next heats.
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21. 6) Slagging and metaltapping:
• After enough molten iron collected the slag hole is
opened and it is collected and disposed off.
• The bolt inserted in the tap hole is knocked out and
the first molten iron is cast with ladled and poured into
the moulds.
• Charging is done simultaneously by layers.
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22. • 5. Cupola Furnace
• :MTunit 1
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23. • 1.Well:
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24. • 1.Well:
• The space between the bottom of tuyers
and the sand bed inside the cylindrical shell of
cupola is called as well.
• Molten metal is collected in this portion.
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25. • 2.Combustion zone:
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26. • 2.Combustion zone OR Oxidizing zone:
• It is located Upper of tuyers.
• Consuming of free oxygen via air blast
and produces tremendous heat.
• Due to oxidation process occurs in silica and manganese
additional heat is generated. (1540°C to 1870°C )
• C + O2 ——→ CO2 + Heat
• Si + O2 ——→ SiO2 + Heat
• 2Mn + O2 ——→ 2MnO + Heat
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27. • 3.Reducing zone OR protective zone:
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28. • 3.Reducing zone OR protective zone:
• It is located in upper level of combustion zone.
• Here CO2 moves upwards and reacts with Coke and
reduced to CO + heat as an
endothermic reaction.
• CO2 + C (coke) ——→ 2CO + Heat
• This reducing atmosphere protected this zone against
oxidation.
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29. • 4.Melting zone:
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30. • 4.Melting zone:
• The charge(iron ore, limestone, coke) starts melting in
this zone and trickles down through coke bed and
collected in well.
• Here carbon content is picked by molten
metal
3Fe + 2CO ——→ Fe3C + CO2
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31. • 5.Preheating zone:
• Here alternate layers of coke bed, flux and metal charge
are there.
• Preheating done here (room temp – 1090 deg)
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32. • 6.Stack:
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33. • 6.Stack:
• The empty portion of cupola above the
preheating zone is called as stack.
• It provides the passage to hot gases
to go to atmosphere.
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34. • Slag is the glass-like by-product left over after a desired
metal has been separated (i.e., smelted) from its raw ore.
Slag is usually a mixture of metal oxides and silicon
dioxide. However, slags can contain metal sulfides and
elemental metals.
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